oliver wrote:I would love to do more, but I think I may have overestimated the amount of rosin in the package :( I've dissolved the entire block and it's already all dissolved! So I think it's far from saturation :(

Oops, You can leave the container open and evaporate some of the IPA. For those planning to follow along at home. Add the IPA to the rosin slowly, and stop when you like the viscosity.

oliver wrote:So I've bought some glycerine from etos, 2.25E so pretty cheap. It's reasonably thick liquid, but according to the contents, it is glycerin and aqua (water i'm sure). Now I'm pretty sure we don't want water in our little mixture :) and thus needs to be removed.

Given the mixture ratio listed before (100ml IPA, 1.5ml Glycerin) I think you can safely ignore the water content of the glycerin.

With 96% IPA there is already water(#1). The rosin and IPA absorb water, they are hygroscopic (#2), glycerin might be but I don't recall.

1: ~4ml give or take some other contaminates, maybe some conversions and/or ratios, and my waning memory =P2: http://en.wikipedia.org/wiki/Hygroscopy , it's the bane of a good brown-sugar/mollasses cookie =(

I actually dumped the rosin into the alcohol, thought it would be way way enough. It wasn't. I guess I could leave it open, but that's just wasteful ;)

Also, if alcohol is the medium, won't some rosin evaporate too?

In regards to the glycerin, I thought the water would be messing things up, especially since I don't know how much water was added! It just lists 'ingredients: glycerin, aqua'. So if I add 1.5ml glycerin-water, how many ml is truly glycerin and what happens if I add too much glycerin. Don't want my house blowing up ;)

Edit: Well I left the bottle open by accident overnight, and it looks like hardly anything if anything evaporated?

oliver wrote:I actually dumped the rosin into the alcohol, thought it would be way way enough. It wasn't. I guess I could leave it open, but that's just wasteful ;)

Also, if alcohol is the medium, won't some rosin evaporate too?

In regards to the glycerin, I thought the water would be messing things up, especially since I don't know how much water was added! It just lists 'ingredients: glycerin, aqua'. So if I add 1.5ml glycerin-water, how many ml is truly glycerin and what happens if I add too much glycerin. Don't want my house blowing up ;)

Edit: Well I left the bottle open by accident overnight, and it looks like hardly anything if anything evaporated?

I expect it will behave like a crystal growth solution. The Solvent evaporates(Water/IPA), and the Solute (Salt/Rosin) ratio increases.

You'll need to do some math and estimating to figure out how to classify your flux. There are ratios listed in the expired patent(Section 4-35), 10-20% = Protective coating, 20-65% = Liquid flux.

I estimate your IPA is 200-350 ml(~= 0.785g/ml, 157-274.75 g), and the rosin blocks are/were 1 ounce(~= 28.35 g). This would be the first type Protective coating.

Re edit: As mentioned above IPA is "a fatty alcohol" and "evaporates slowly". You literally have a bottleneck in the vaporization chamber =)

It's only 100ml bottle :D. I don't know how much the rosin block was, but I fully take your word on it (wasn't listed on the package).

I'm supprised that it evaporates so slowly (in the bottle after mixing). I've spilled a bottle once and it was gone within an hour or so. Mind you, this is 96% Ethanol, with water, of course, Methylethylketon and Linalyacetate (both for the oder and posioning bit?). I"ll let it evaporate more, what's the worst that can happen? Rosin won't evaporate with it, so only the ratio can increase. The alcohol actually could take some water with it? Right?

I tried making flux from an even more raw material, pine gum straight from the tree. It had to be filtered, of course, but so far so good -- and the turpentine in it hasn't eaten through my bottle yet. :)

It's so interesting to read about people's ways at the other side of the planet :)

The case is in USSR (and now in Russia) rosin is a most popular flux. From 1930 and up to our days every schoolboy used solid rosin or rosin solution for his hobby, and even in industrial electronics assembly rosin was #1 flux ever. The reason is DIY electronics making was not just a hobby: soldering and electronics skill was a virtue, approved by society and authorities :) And as the rosin is easy to obtain and prepare, it was extremely popular.

Even nowadays electronics hobbyists prefer using solid rosin. Usually a drop of rosin is placed onto the tip, then solder is added onto the tip as well, and this hot mixture is brought onto the printed pad or wire. As rosin evaporates very slowly, this mixture successfully flows onto metal and remove all oxidations.

Btw, we prefer making liquid rosin flux with ethanol. I tried IPA too and it works, but ethanol smells better :)

Of course today we have modern water soluble fluxes, but sometimes it's still a nice idea to make some rosin solution and use it as flux.

To prepare rosin from raw resin (sap, gum) you just need to place resin in metal container and heat that container up until resin melts. Then keep rosin melted for about some minutes. Some crap like bark particles will emerge, so you should remove it. Turpentine wil evaporate, and soon you will have amber-like mass, good for using as flux.